Introduction

Interferometric devices cause interferences between two or more waves. Interferometers are usually classified in two different groups. The first one deals with wavefront-splitting devices: a primary wavefront is divided in two spatially different beams that follow different paths before they are recombined and produce interferences. For example, the Young holes system configuration is part of this group. The second group deals with amplitude-splitting devices: a primary wavefront is divided in two spatially equal beams that follow different paths before they are recombined and produce interferences. The Michelson interferometer is part of this group.

The next paragraphs present the devices of both groups. The description of a Twyman-Green interferometer and the spectroscopy principle by Fourier transform and by Fabry-Perot will be developed in the case study. The principle of a laser Doppler velocimeter will be studied in the exercise part.